This is my first time dealing with this type of equipment, and I want to install everything correctly. I'm planning on putting the power amp in the bottom two rack spaces to keep the rack bottom-heavy. Will I need those rack wing thingies for the rear of the power amp if I do this? Also, would it make more sense to install the amp higher in the rack since it will be generating lots of heat? Are there any other things I should keep in mind when I put this thing together?

Since the RMX is so heavy, its a good idea to use the rear rack ears. That will help make the rack more structurally solid overall, and it will keep the weight of the amp from torquing on the front ears and the rack rails.

I would mount it on the bottom to keep the rack bottom-heavy, like you said. The QSC draws air in the back and blows it out the front, so you don't need to worry so much about circulation above and below it. That said, if you have any rack spaces left over, keep a space open above the amp.

i just got a rmx2450 and a skb 8 space last week. but i don't know what yuo mean by mounting it from the rear? i am interesting because it does way alot and i don't want my rack getting bent out of shape. also my dumb a** put everything in up side down and i had to switch everything around let me say after that thing is in there it is not fun taking it back out. also yuo might want to thing about getting vent panel they make a rack look bad a**, and they cost like $7.